How to Read Your Tire Size (It Takes 30 Seconds)

July 25, 2026 · ExtraBrake

Walk up to any car and look at the tire's sidewall. Between the brand name and the tread, you'll find a marking like 205/55R16 91V. That one line tells you everything you need to order the right tires online — no mechanic required.

Breaking it down

• 205 — the tire's width in millimeters, measured sidewall to sidewall.
• 55 — the aspect ratio: the sidewall's height as a percentage of the width. Lower numbers mean a lower, sportier profile.
• R16 — "R" for radial construction (virtually every modern tire), and 16 for the wheel diameter in inches it fits.
• 91 — the load index: how much weight each tire can safely carry (91 = 1,356 lbs).
• V — the speed rating: the maximum sustained speed the tire is built for (V = 149 mph).

Where else to find your size

If you'd rather not crouch next to your wheel, the same size is printed on the driver's door jamb sticker and in your owner's manual. One caution: use the sticker or your current tires, not guesswork — a tire that's off by one size can rub the wheel arch or throw off your speedometer.

Ordering with your size

At ExtraBrake, the search works exactly the way the sidewall reads: pick your width, profile and rim in the size finder, and you'll only ever see tires that fit. You can also type the whole thing — "205/55R16" or even "2055516" — into the search bar. When you buy, match or exceed your original load index and speed rating; going lower is a safety compromise.

One last tip: order all 4 at once. A matched set wears evenly and handles predictably — and it's how we keep the per-tire price low.